The present disclosure relates to Fibre Channel loops, and more specifically to detecting and bypassing node ports in an OLD-PORT state.
Electronic data systems are often interconnected using network communication systems. Approaches that have been developed for computer network architectures include area-wide networks and channels. Traditional networks (e.g., LAN""s and WAN""s) may offer flexibility and relatively large distance capabilities. Channels, such as the Enterprise System Connection (ESCON) and the Small Computer System Interface (SCSI), have been developed for high performance and reliability. Channels often use dedicated short-distance connections between computers or between computers and peripherals.
Features of both channels and networks have been incorporated into the Fibre Channel standard. Fibre Channel systems combine the speed and reliability of channels with the flexibility and connectivity of networks. Fibre Channel products often run at high data rates, such as 266 Mbps or 1062 Mbps. These speeds are sufficient to handle quite demanding applications, such as uncompressed, full motion, high-quality video.
There are at least three ways to deploy a Fibre Channel network, which include simple point-to-point connections, arbitrated loops, and switched fabrics. The simplest topology is the point-to-point configuration, which simply connects any two Fibre Channel systems directly. Arbitrated loops are Fibre Channel ring connections that provide shared access to bandwidth via arbitration. Switched Fibre Channel networks, called xe2x80x9cfabricsxe2x80x9d, are a form of cross-point switching.
Conventional Fibre Channel Arbitrated Loop (FC-AL) protocols provide for loop functionality in the interconnection of devices or loop segments through node ports. However, direct interconnection of node ports may be problematic since a failure at one node port in a loop may cause failure of the entire loop. This difficulty may be overcome in conventional Fibre Channel technology through the use of hubs. Hubs may include a number of hub ports interconnected in a loop topology. Node ports are connected to hub ports, forming a star topology with the hub at the center. Hub ports which are not connected to node ports or which are connected to failed node ports are bypassed. Therefore, the loop may be maintained despite removal or failure of node ports.
The present disclosure includes a hub port in a Fibre Channel loop for detecting and bypassing attached node ports in an OLD-PORT state. The hub port includes a hub data source, a detect circuit, and an output control circuit.
The hub data source supplies data to the hub port from a Fibre Channel loop. The detect circuit is configured to detect a valid non-Arbitrated Loop sequence from an attached node port indicating that the node port is in an OLD-PORT state. The output control circuit operates to bypass the node port from the loop when the valid non-Arbitrated Loop sequence is detected.
The present disclosure also includes a method for detecting and-selectively bypassing an attached node port in an OLD-PORT state. The method includes detecting a valid non-Arbitrated Loop sequence from a node port, and appropriately bypassing the node port.